Dry friction clutch/brakes depend upon the rubbing of a dry friction material against dry reaction members to start and stop a press. This continuous dry rubbing causes wearing of both the friction material and the reaction members as well as causing the generation of heat in these members. The faster the press operates and the faster the flywheel rotates, greater is the amount of wear and heat which are generated. This generation of wear and heat requires periodic gap adjustment between the friction plates and the reaction members to keep the clutch/brakes functioning and the press operating correctly. The trip rate or cycle speed of a press equipped with a dry friction clutch/brake unit is limited because the mass of the unit determines its heat dissipation capacity. If the mass of the unit is increased to increase its heat dissipation capacity, the inertia that must be started and stopped is also increased. These factors define a closed loop from which it is impossible to escape when trying to substantially increase the performance of the system.
Press drives incorporating oil shear brake and clutch units have been developed to eliminate the problems associated with the dry friction type of units. The oil shear systems use hydraulic actuation instead of air actuation and the units have been developed with key modules which can be easily adapted to be mated with the various types of presses. Properly designed oil shear clutch/brake drives offer the advantage of little or no wear of plates in the disk stacks and no brake fade. This provides a more precise operation of the press and dramatically increases press up-time. The oil film between the adjacent disks carries the heat generated by the start-stops of the unit away from the disk stacks. This removal of heat offers the advantage that there is now no practical limit for the press trip rate and the flywheel speed. In addition, this removal of heat provides unlimited inching capabilities.
While these oil shear clutch/brake drive units have significantly improved the operation of the units, providing a continuous and adequate supply of coolant oil to these oil shear clutch/brake drive units has been the subject of continuous development. Originally, cooling oil was supplied to the inner diameter of the clutch and the brake and was removed from the outer circumferential area of the clutch and brake. The cooling oil thus flowed in the same direction as the centrifugal force exerted on the cooling oil by the rotation of the components of the clutch/brake units. Experimentation has shown that by reversing the flow of oil, such that the oil flows against the centrifugal force exerted upon the cooling oil by rotation of the components of the clutch/brake units, an improved lubrication system can be obtained. Accordingly, what is needed is a design for a press drive which is capable of reversing the flow of cooling oil to the brake and clutch units in the press drive.